Pin-head electric lamp and method of manufacture



H. S\NANSON Nov. 19, 1940.

PIN HEAD ELECTRIC LAMP AND METHOD OF MANUFACTURE Filed April 18, 1940 m Ill Wnesses:

/MZM/L W /M Nov. 19, 1940. H. SWANSON 2,222,093

PIN HEAD ELECTRIC LAMP AND METHOD OF MANUFACTURE Filed April 18, 1940 6 Sheets-Sheet P,

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PIN HEAD ELECTRIC LAMP AND METHOD OF MANUFACTURE Filed April 18, 1940 6 Sheets-Sheet 54 '58W l J/ M Il lsl l, |55

i l W l 1 I s/ 4 Wifnesses: Inventor' H. SWANSON Nov. 19, 1940.

PIN HEAD ELECTRIC LAMP AND METHOD OF MANUFACTURE Filed April 18, 1940 6 Sheets-Sheet 4 l Inventor H. SWANSON Nov. 19, 1940.

lIN HEAD ELECTRIC LAMP AND METHOD OF MANUFACTURE Filed April 18, 1940 6 Sheets-Sheet 5 las , InvenTor 4 m n m H. SWANSON Nov. 19, 1940.

PIN HEAD ELECTRIC LAMP AND METHOD OF MANUFACTURE Filed April 18, 1940 6 Sheets-Sheet 6 fd-*2.20 l

Wi'Tnesses:

Inventor Mm w MM5-1 m ma Patented Nov. 19, 1940 UNITED STATES PATENT Harold Swanson, Cleveland, Ohio Application April is, 194e, serial No. .nach

` iv claims. (ci. 17cm-.isi

lll'his invention relates to improvements to construct extremely small electric lamps and similar articles.

@ne object of this invention is to show a practical means of constructing an electric lamp and similar articles that compares in size with the dimensions of the head of a common household or clothing pin.

il further object is to show that the improvements set forth in my original application, Serial Number 744,598, nled Sept. 18, 1934, now a patent for an electric incandescent high pressure gas lamp, Patent Number 2,097,679, patented Nov. 2, 1937, and continued in application, Serial Number locll, filed Sept. 29, 1937, Patent Number 2,397,732, patented Nov. 22, 1938, and also continued in application, Serial Number 190,615, l'llecl Feb. 15, 1938, Patent Number 2,154,542, patented April 18, 1939, are adaptable to make extremely small electric lamps and similar articles.

.-l further object is that this invention shall be a continuation of my earlier inventions mentioned in the preceding paragraph, in respect to Where any improvements or subject matter of my earlier inventions can be used to an advantage with the improvements of this invention, particularly the use of hollowmet'al wires and their many teatures which are described in the previous applica tions or patents and in this application.

a further object is that the small electric lamps described herein can be substituted for the small electric lamps as mounted and described in the applications and patents referred to in the two preceding paragraphs.

A further object is to show that by using the improvements described herein, it is possible to build electric lamps that will be smaller as to minuteness than any electric lamp which is constructed by previously known means; therefore these small electric lamps which I choose to call herein pin-head electric lamps, might be appropriately called the smallest lamps irly the World.

A further object is that these pin-head electric lamps can be constructed as; electric incandesm cent lamps of vacuum, low pressure gas, or high pressure gas types; electric metallic vapor filament `type lamps; electric metallic vapor arc lamps of the low pressure or the high pressure types; electric glow lamps of the low pressure gas or the high pressure gas types.

@ther objects of this invention will appear more fully described and illustrated hereinafter.

While it is practical to adapt the improvements of this invention to a large variety of small electric lamps, the present Patent Oflice regulations restrict the claims that are allowed in a single patent which illustrates more than three types. In the accompanying drawings I have illustrated several types to show that ll have not overlooked the possibility of many variations in types of lamps to apply these improvements; however in the drawings, several features are common with those types illustrated by the following in which: l0

Fig. l to Fig. 6 are enlarged sectional views of individual pin-head electric lamps.

Fig. 'l to Fig. 12 are enlarged sectional views of the bulbs for pin-head electric lamps.

Fig. 13 to Fig. 21 are enlarged sectional views 15 of the progressive operations in constructing one of the individual pin-head lamps.

Fig. 22 is an enlarged sectional and elevational View of a multiple string of pinhead electric lamps arranged in position lor exhausting, filling and iinal sealing.

Fig. 23 and Fig. 24 are enlarged sectional and elevational views of multiple strings of pin-head electric lamps.

Referring to Fig. l Whichis an enlarged sectional 25 view of a pin-head electric incandescent lamp; having two hollow metal Wires I and 2 hermeticaliy sealed by glass fusion into the glass'bead at t and to form the lamp bulb 5'; a coiled lamp filament 6 is slipped over the ends of two electric 30 lead-in wires 'l and t that are separated a suhcient distance for the lamp filaments lighting re` quirements, and spot Welded or fastened to the lead-ln wires at 9 and lll forming the filament mount; the filament mount is placed within the lamp bulb 5 and the hollow metal Wires l and 2 are compressed against the lead-in wires 9 and i il to hold the njlament mount in place without en tirely closing oi the passage for exhaust (see lig. 18) after which the lamp bulb is exhausted 49 to a vacuum, or exhausted and lled with an inert gas at either low or high pressures through the hollow metal wires l and 2 which are swaged around or flattened and cut oil' with the lead-in wires 9 and lll to form the preliminary seals at i i 45 and i2, after which the ilnal seals at i3 and lll are made by either electric Welding, bracing, soldering or otherwise closing the ends air tight; thus making the electric lamp. i

Referring to Fig. 2 which is an enlarged sec- 5G tional view of a pin-head electric incandescent lamp; having two filament supports l5 and iB that are made from nickel or any low thermal expansion metal rod, each turned on the outside diameter to form steps l1, it, and i9, on one support and steps 20, 2|, and 22 on the other sup.- port, with slots 23 and 24 cut in each; a coiled lamp filament 25 is slipped over the filament sup ports I5 and I6 on their respective steps I9 and 22 and spot welded thereto at 26 and 21 to form the filament mount; the filament ,mount is placed within two hollow metal wires 28 and 29 that are separated a sufficient distance for the lamp filaments lighting requirements and spot welded 'or slightly compressed against the supports l5 and I6 on their respective steps I1 and 20 to hold the filament mount in place; a glass bead or bulb 30 is placed over the hollow metal wires 28 and 29 and hermetically sealed thereto by glass fusion at 3| and 32; after which the lamp is exhausted to a vacuum, exhausted and filled with an inert gas at either low or high pressures through the hollow metal wires 28 and 29 which are swaged or fiattened and cut off to form the preliminary seals at 33 and 34, after which the nal seals at 35 and 36 are made by either electric welding, brazing, soldering, or otherwise closing the ends air tight; thus making the electric lamp.

In Fig. 1 and Fig. 2, it is obvious that the lamp filaments can be made of close wound coils and mounted on the filament supports within the hollow metal wires butted end to-end (see Fig. 13) then when the glass bead or bulb is hermetically sealed and is still in a plastic state, the hollow metal wires can be pulled apart with the filament supports, thereby separating the lamp filament coils where they are free to slip on the ends of the filament supports. The finished lamps will be the same as is shown in Fig. 1 and Fig. 2.

Referring to Fig. 3 which is an enlarged sectional view of a pin-head electric incandescent lamp; having a close wound coil lamp filament 31 inserted into the ends of two hollow metal wires 38 and 39 that are butted end to end and spot welded or slightly compressed to hold the lamp filament 31 in place at 40 and 4I; a glass bead or bulb 42 is placed over the hollow metal wires 36 and 39 at their junction and hermetically sealed thereto by glass fusion at 43 and 44 and while the glass bead or bulb 42 is still in a hot plastic state, the hollow metal wires 38 and 39 are pulled apart, thereby separating the coils of the lamp filament 31 and exposing them for their light to pass through the bulb 42 which can be blown, to enlarge if desirable; after which the lamp i`s exhausted to a vacuum, or exhausted and filled with an inert gas at either low pressure or high pressure through the hollow metal wires 38 and 39 which are swaged or flattened and out off to form the preliminary seals at 45 and 46, after which the final seals at 41 and 48 are made by either electric welding, brazing, soldering or otherwise closing the ends air tight; thus making the electric lamp. When inserting the close woundeoil lamp filament 31 in the ends of the hollow metal wires 38 and 39, a close fitting removable mandrel within the coil filament 31 will facilitate its insertion into the hollow metal wires; or the coil filament 31 can be tightly wound upon a lead, tin, or any other low fusing metal mandrel than can be removed by melting when the glass bulb 42 is heated, or it can be removed by vaporizing with an electric induction furnace with the hollow metal wires 38 and 39 connected to a vacuum line before or after the hermetic seals at 43 and 44 are made.

Referring to Fig. 4 which is an enlarged sectional view of a pin-head electric incandescent lamp; having a coil lamp filament 49 with two filament support tubes 50 and 5I spot Welded or clamped over the endsto form vthe filament mount; the filament mount is placed within two hollow metal wires 52 and 53 that are separated a suiicient distance for .the lamp filaments lighting requirements andI compressed against the filament supports 50 and 5I to hold the filament mount in place without entirely closing off the passage for exhaust (see Fig. 18) a glass bead or bulb 54 is hermetically sealed by glass fusion at 55 and 56 to the hollow metal wires 52 and 53; after which the lamp is exhausted to a vacuum, or exhausted and filled with an inert gas at either low or high pressures through the hollow metal wires which are swaged or flattened and cut off to form the preliminary seals at 51 and 58, after which the final sealsat 59 and G0 are made by either electric welding, brazing, soldering, or otherwise closing the ends air tight; thus making the electric lamp.

In Fig. 4 it is obvious that the lamp filament 49 can be made a close wound coil with other operations performed for sealing and separating the coils as previously referred to for the lamps in Fig. 1 and Fig. 2.

Referring to Fig. 5 which is an enlarged sectional view of a pin-head electric incandescent and metallic Vapor are lamp; having a coiled lamp filament 6| slipped over two tungsten or high temperature heat resisting arcing electrodes 62 and 63 that are free from contact with the filament 6l except where they are spot welded together at 64 and 65; mounting the electrodes 62 and 63 with the filament 6I thereon within two hollow metal wires 66 and 61 that are separated a-sufilcient distance for the lamps lighting requirements and clamped against the electrodes 62 and 63 to hold the filament 6| and set the arcing space 68 in place without entirely closing ofi the passage for exhaust (see Fig. 18) a glass bead or bulb 69 is hermetically sealed by glass fusion at 10 and 1l to the hollow metal wires 66 and 61; after which the lamp is exhausted to a vacuum and filled with a quantity of mercury 12 that is equal to approximately one-tenth (T16) of the entire inside volume of the lamp, through the hollow metal wires 66 and 61 which are swaged around the electrodes 62 and 63 to form the preliminary seals 13 and 14, after which the nal seals at 15 and 16 are made by electric welding or otherwise closing the ends air tight; thus making the electric lamp.

In Fig. 5 it is obvious that the lamp can be made to operate as a high pressure mercury arc lamp or a low pressure mercury arc lamp; which depends upon the relative parts of the lamp together with conditions under which the lamp operates, such as the lamp operating voltage and current supply amperage, the filament size and length, the size of the electrodes and the arcing space distance, quantity of mercury therein, if the lamp has a vacuum or is gas filled, or the electronic emission from the lamp filament and the electrodes. The lamp can be filled with a predetermined high pressure gas such as hydrogen to build up a very high are resistance or it can be filled with a low pressure ionizing gas such as neon to makela low arc resistance; then by mixing two or more inert gases (meaning chemically inert to the lamp parts) and by varying the gas pressure within the lamp, a Very wide combination of operating characteristics of the lamp can be obtained; also the lamp filament 6| and the electrodes 62 and 63 can be coated with electronic emission substances, such as compounds of thorium, polonium, uranium, or radium in small 75 hill quantities, ionium, or any radioactive rare-earth compounds, or impregnated (sometimes called alioyed) with such electronic emission substances by mixing them with reduced metallic powder from which the filament 6| or electrodes 62 and (i3 are made during their manufacturing processes to give a high electronic emission when they are heated Within the lamp. This high electronic emission from the filament 6| and the electrodes t2 and 63 rapidly ionizes the gases within the lamp which in turn starts the electronic fiow to produce the electric arc across the arcing space 68 between the electrodes 62 and 63 and radiates light.

Referring to Fig. 6 which is an enlarged sectional view of a pin-head electric glow or metallic vapor arc lamp; having two arcing electrode buttons ll and 'i0 fastened to two electrode rods 'lil and 80; mounting the electrode rods |9 and 80 with the electrodebuttons 'll and 'i0 thereon within two hollow metal wires 3| and 82 that are separated a suilicient distance for the lamps lighting requirements and clamped against the electrode rods i9 and 30 to hold the electrode buttons il and lt that set the arcing space |33 in place without entirely closing off the passage for exhaust (see Fig. 18) a glass bead or bulb 84 is hermetin cally sealed by glass fusion at 85 and B6 to the hollow metal wires BI and H2; after which the lamp is exhausted and filled with neon or any other ionizing gas or mixture of gases at either low or high pressures, and also lled with a quantity of mercury dl that is equal to approximately one-tenth (11s) of the entire inside volume of the lamp, lthrough the hollow metal wires iii and di which are swaged around the electrode rods lil `and 30 to form the preliminary seals at 80 and du, after which the nal seals at 9h and 9| are made by electric welding or otherwise closing the ends air tight; thus making the electric lamp.

lin Fig. o it is obvious that the lamp can be made to operate as a low pressure gas glow lamp, a high pressure gas glow lamp, a high pressure mercury arc lamp, or a low pressure mercury arc lamp; having `other variable features and char-n acteristics as previously referred to in connection with the lamp in Fig. 5.

ln Fig. 5 and Fig. 6, for convenience of drawing the illustration, I have shown the mercury 'il and 3l in a level pool within the lamp. After the lamp has once been lighted the mercury would be in the form of little droplets or globules clinging all over the inside surfaces of the lamp. Also the quantity of mercury Within each lamp i' could vary from a trace up to a maximum amount needed which very rarely would exceed one-tenth (Tis) of the entire inside volume of each lamp. it is also evident that other low vaporizing metals such as sodium, potassium, or any other metal or alloy could be substituted for the mercury l2 and lll within the lamps.

Referring to Fig. 7 which is an enlarged sectional view of a pin-head electric lamp bulb;

having a glass bead or bulb 92 which is bored out mechanically or drawn out by heating to a plastic state as in glass blowing methods to form the small capillary hole 93 and also the bell--mouth enlargements 9| and 95 extending therefrom; two hollow metal wires 96 and 9i with ends tapered and rounded at 9B and 99 are inserted into the bell-mouth enlargements gli and 95 and hermetically sealed by glass fusion with the glass bead or bulb 92 at |00 and |0i; thus making the electric lamp bulb.

Referring to Fig. B which is an enlarged sectional view of a pin-head electric lamp bulb; having a quartz pebble or transparent gem |02 which is bored out mechanically to form the small capillary hole |03 and also the bell-mouth enlargements |04 and |05 extending therefrom; two hollow metal wires |05 and |01 with the ends tapered and rounded at |08 and I 09 are inserted into the bell-mouth enlargements |04 and l05;

the gem |02 is cleaned and the outside surface isv coated with a film of sodium silicate solution and dried for glass fusion with it; the gem |02 with the hollow metal wires i 08 and |01 inserted therein are placed within a glass bead or bulb I| and all hermetically sealed together by glass fusion at |il, |I2 and H3; thus making the electric lamp bulb.

In Fig. 'l and Fig. il, the pin-head electric lamp bulbs are intended to be used with small electric incandescent high pressure metallic vapor filament lamps, or they can be substituted for a metallic vapor filament capillary tube as described in my invention previously referred to as Patent Number 2,154,542, patented April 18, V1939.

Referring to Fig. 9 which is an enlarged sec tional View of a pin-head electric lamp bulb; having a quartz pebble or transparent gem llll which is bored out mechanically to form the hole H with chamfers ||5 and ill; the gem lill is cleaned and the outside surface is coated with a film of sodium silicate solution and dried for glass fusion with it; two hollow metal wires |||l and d are butted against the gem i M and placed within a glass bulb im (two removable pointed mandrels in the hole chamfers lili and ill of the gem ||4 passing through the hollow metal wires i8 and I9 will hold them centrally) which are all hermetically sealed together by glass iu sion at |2|, |22 and |23; thus making the electric lamp bulb.

Referring to Fig. l0 which is an enlarged sectional view of a pin-head electric lamp bulb; havn ing a quartzV pebble or transparent gem |24 which is bored out mechanically to form the hole |25 that will closely fit with the ends of the two hollow metal wires |25 and ill (the ends of the hollow metal wires itt and ill can be tted to the hole |25 in the gem Wil; or the hole |25 in the gem |24 can be made slightly tapered from the outside to the center to fit the ends of the hollow metal wires Ht and lll); the gern |24 is cleaned and the outside surface is coated with a lm of sodium silicate solution and dried for glass fusion with it; the gem im with the hollow metal wires |26 and |21 inserted therein are placed within a glass bulb We and all hermetically sealed together by glass fusion at its, i3d and i3 l; thus making the electric lamp bulb.

Referring to Fig. ll which is an enlarged sectional view of a pin-head electric lamp bulb; having a quartz pebble or transparent gem |32 which is bored out mechanically to form the bell-mouth hole |33; two hollow metal wires i3d and |35 with the ends tapered at |30 and lol are -fitted to the bell-mouth hole |33; the gem |32 is cleaned and the bell-mouth hole |33 is coated with a iilm of sodium silicate solution and dried for glass fw sion with-it; glass beads itil and |39 are hermetically sealed by glass fusion with the hollow metal wires |34 and |35 at illu and Ml and are inserted into the hole |33 of the gern |32 and also hermetically sealed by glass fusion at |42 and |43; the surplus sodium silicate within the bell-mouth hole |33 can be washed away by iorcing chemical solutions and rinsing with pure water through the hollow metal wires |34 and |35; a dilute solution of water and sulphuric acid with a little hydrofluoric acid added makes one type of chemical solution; any slight dissolving of the inside of the hollow metal wires |34 and |35 will not be objectionable; thus making the electric lamp bulb.

Referring to Fig. 12 which is an enlarged sectional view of a pin-head electric lamp bulb; having two hollow metal wires |44 and |45 butted end to end (see Fig. 13) with a removable mandrel therein; grains or particles of crushed quartz pebble or transparent gem |46 (several shown) are cleaned and immersed in a dilute solution of sodium silicate so as to have avery thin film coating of it thereon and dried for glass fusion with them; mixing powdered glass with the grains |46 and forming into a moulded bead or bulb |41 under mechanical pressure; the moulded bead or bulb is placed over the hollow metal wires |44 and |45 attheir junction and hermetically sealed thereto by glass fusion at |48 and |49 and while the glass of the bead or bulb |41 is still in a hot plastic state, the hollow metal wires |44 and 45 are pulled a fixed distance apart; the bead or bulb can also be made by building up and fusing the grains |46 with the powdered glass on the ends of the hollow metal wires |44 and |45; thus making the electric lamp bulb.

In Fig. 12, the pin-head electric lamp bulbwill give light diffusion without much light absorption. If the fusing processes are done in a high vacuum, the bulb will be more transparent with less light diffusion, otherwise the bulb is milky or white with light diffusion. About five percent (5%) of the light is lost but maximum light diffusion is obtained.

Referringto Fig. 13 on through to Fig. 2l which are enlarged sectional views of the progressive operations in constructing a pin-head electric incandescent lamp; having identical parts numbered with the same number where they appear in any of the views even though those numbers are not mentioned in the descriptive caption for the figure where those numbers are repeated; and having in Fig 13 a glass bead or bulb |50 slipped over twohollow metal wires |5| and |52 butted end to end with a removable heat resisting mandrel |53 inserted through them and clamped between jaws |54, |55, |56 and |51 of one fixture; the glass bead or bulb |50 is placed over the junction of the hollow metal wires |5| and |52 and the gas flames |58 and |59 are directed thereon until the bulb |50 is hermetically sealed by glass fusion to the hollow metal wires |5| and |52 in Fig. 14 at |60 and |6| and while the glass bead or bulb |50 is still in a hot plastic state, the hollow metal wires |5| and |52 are pulled a fixed distance apart with their respective'jaws |54, |55, |56 and |51 of the fixture; thus making the lamp bulb assembly. In Fig. 15 the lamp bulb assembly is slipped over one electric lead-in wire |62 and a coiled lamp filament |64 is slipped over another electric lead-in wire |63; the lead-in wires |62 and |63 are clamped between the jaws |65, |66, |61 and |68 of another fixture so as to set the iilament space |69. In Fig. 16 the filament |64 is placed centrally over the filament space |69 (see Fig. 15) and clamped or spot welded at and |1| to form the filament mount. In Fig. 17 the lamp bulb assembly is centrally placed over the lamp filament |64 and the hollow metal wires |5| and |52 are compressed against the lead-in wires |62 and |63 at |12 and |13 to hold the filament mount in place without entirely closing off the passage for exhaust as shown by cross-section in Fig. 18; thus making the lamp bulb andiilament mount assembly which is removed from this fixture. In Fig. 19 the hollow metal wire |5| of the lamp bulb and filament mount assembly is freely inserted into an exhaust and gas filling adaptor that is connected to gas filling equipment, in which a compression type rubber ring |14 is held in a fixed sleeve that encloses the compression plunger |16. In Fig. 20 the compression plunger 16 compresses the rubber ring |14 and by volume displacement the rubber ring |14 compresses and closes in around the hollow metal wire |5|. 'I'he lamp bulb and filament mount assembly is heated to drive off moisture and air that is held against the inside surfaces by capillary, surface and static attraction, and at the same time a hydrogen gas is forced through the lamp in and out simultaneously through the hollow metal wires |5| and |52 to drive out the air and moisture and also clean the filament |64 as an electric current lights up the filament |64 to incandescence by connecting the electric supply line to the hollow metal wires |5| and |52 for a short interval of time; a nitrogen flushing gas drives out the hydrogen and then an argon flushing gas drives out the nitrogen, displacing the inside volume with argon (usually a mixture of argon, 20% nitrogen, and traces of rare atmospheric gases such as neon, krypton and others makes the best inert filling gas) the hollow metal wire |52 is then mechanically iiattened at |13 to prevent too much filling gas from escaping and also to form one preliminary seal; when the filling gas has reached the desired pressure (either low or high pressure) within the lamp, the other hollow metal wire |5| is mechanically flattened at |12 to form the other preliminary seal; the lamp is then removed from the gas filling adaptor by releasing the compression plunger |16 which allows the compression rubber ring |14 to open itself; the ends of the hollow metal wires |5| and |52 and the lead-in wires |62 and |63 are cut oli at |11 and |18. In Fig. 21, the final seals at- |19 and |80 are made by either electric welding, brazing, soldering, or otherwise closing the ends air tight; thus making the electric lamp.

Referring to Fig. 22 which is an enlarged sectional and elevational view of a multiple string of pin-head electric incandescent lamps connected together in simultaneous exhaust, fill, and final seal arrangement; having similar parts numbered with the same number where they appear with each lamp; the lamps are made as individual lamps except that they are connected together, exhausted, filled, and finally sealed aS a single unit assembly; having a coiled lamp filament |8|V slipped over the end of a rst electric lead-in wire |82 and clamped or spot welded together at |83 which are both inserted into the end of a rst hollow metal wire |84 which is compressed against the lead-in wire |82 at |85 to hold the lamp filament 8| and the lead-in wire |82 in place without entirely closing ofi:` the passage for exhaust (see Fig. 18); a second lead-in wire |86'is slipped into the end of the filament |8| and clamped or spot welded together at |81; a glass bead or bulb |88 is slipped over the end of a second hollow metal wire |89 which is slipped over the second lead-in wire |86 and filament |8| the second hollow metal wire |89 is compressed against the lead-in wire |86 at |90 to hold the lamp filament |8| and the leadin wire |86 in place without entirely closing 0H lll huil

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the passage for exhaust (see Fig. 18); the ends of the hollow metal wires |84 and |89 and the ends of the lead-in wires |82 and |86 were separated a suflicient distance for the lamp filamentls lighting requirements when they were previously set in place; the glass bulb |88 is centrally located over the filament |8| and hermetlcally sealed by glass fusion to the hollow metal wires |801 and |89 at |9l and |92 and while the glass bead or bulb |88 is still in a hot plastic state, the inside diameter can be slightly enlarged by blowing air under pressure into the bulb |88 through the hollow metal wires |84 and itil; thus making one lamp of the string. rlhe second lamp of the string is made similar to the rirst lamp except that the second hollow metal wirel |89 or the first lamp becomes the rst hollow metal wire of the second lamp. The third, fourth, fifth, etc., lamps are made similar to the second lamp. For convenience of identincation here, the last hollow metal wire is numbered lll. The entire string of lamps are er.- hausted, lled, and nally sealed as a unit as sembly similar to a single lamp with the same operations performed as previously described for the lamp in Fig. 19, Fig. 20 and Fig. 2l; thus making the string of electric lamps.

The string of electric incandescent lamps in Fig. 22 can beA connected electrically to burn in either series, parallel, or series parallel circuits evcn though the gas chambers of each lamp are all interconnected; also the number oi lamps in the string or the distance between the lamps can be as desired.

Referring to Fig. 23 which is an enlarged sectional and elevational view of a multiple string of pin-head electric glow or metallic Vapor arc lamps; having similar parts numbered with the same numbers where they appear with each lamp; the lamps are made as individual lamps except that they are connected together, exhausted, filled, and nally sealed as a single unit assembly; having a first arcing electrode button itil fastened to a first electrode rod |955; mounting the electrode rod lflli with the electrode button |9ll thereon within a rst hollow metal wire igt and clamped against the electrode rod lllt at lill' to hold it in place without entirely closing ofi the passage for exhaust (see Fig. 18); a second arcing electrode rod i9@ with a groovecl sleeve |199 centrally fastened thereon and a second and third arcing electrode buttons tilt and lllll fastened on the ends thereof which are centrally placed within a second hollow metal wire fili Til

lll

lili and clamped or spot welded at 20d to hold it in place; a glass bead o-r bulb Zilli is centrally located over the electrode buttons lgl and mit that are held at a xed distance apart for the arcing space Zilli and hermetically sealed by glass fusion to the hollow metal wires ist and mil at Zilli and Zilli; thus making one lamp of the string. The second lamp of the string is made similar to the iirst lamp except that the second hollow metal wire 202 of the iirst lamp becomes the iirst hollow metal wire of the secand lamp. The third, fourth, ith, etc., lamps are made similar to the second lamp. The last lamp in the string is made the same as the :first lamp, having a similar hollow metal wire it, electrode rod |95, and electrode button ist; after which the string of lamps are exhausted and iilled with neon or any other ionizing gas or gas mixture at either low or high pressures and also filled with a quantity of mercury 203, that is equal to approximately one-tenth (11e) of the entire inside volume ol. the string of lamps,

through both. end hollow metafwlres |96 (one end shown) which are swaged around the end `electrode rods |95 to form the preliminary seals tional and elevational view of amultiple string of pin-'head electric incandescent and metallic vapor arc lamps; having similar parts numbered with the numbers where they appear with each lamp; the lamps are made as individual lamps except that they are connected together, exhausted, -lled, and iinally sealed as a single unit assembly; having a coiled lamp lament dit slipped over a first tungsten or high tempera ture heat resisting arcing electrode 2li that is free from contact with the filament Zlll except where they are spot welded together at 2li; mounting the electrode 2li with the larnent 2id thereon within a lirst hollow metal wire 2id which is clamped against the electrode 2li at 2li to hold it in place without entirely closing ofi' the passage for exhaust (see Fig. 18),', a second tungsten or high temperature heat resisting arcing electrode Zit with a grooved sleeve ll centrally fastened thereon is slipped into the rlrst iilament ZIO while a second coiled lamp filament 2li is slipped over the other end of the electrode 2lb that is free from. contact with both laments lllll and 2|lv except where they are spot welded together at Zl and 2id; a second hollow metal wire 22ll is centrally located over the grooved sleeve Zit which is clamped or spot welded thereto at 22l to hold it in place; a glass bead or bulb 222 is centrally located over the iilarnent Zlll and the electrodes till and llt that were previously set at a xed distance apart .for the arcing space 223 and hermetically sealed by glass fusion to the hollow metal wires its and till at 224i and 225; thus making one lamp oi the string. The second lamp oi the string is made similar to the nrst lamp except that the second hollow metal Wire 22ll of the first lamp becomes the rst hollow metal wire oi the seeond lamp. The third, fourth, fifth, etc., lamps are made similar to the second lamp. The last lamp in the string is made the same as the Erst lamp, having a similar hollow metal wire 2 it and electrode 2li; after which the string of lamps are exhausted to a vacuum or exhausted and lled with an inert gas at either low or high pressures together with a quantity of mercury" 226, that is equal to approximately one-tenth (le-l of the entire inside volume of the string oi' lamps, through the end hollow metal Wires ilill (one end shown) which are swaged around the end electrode rods 2li to form the preliminary seals at lill; after which the nal seals at 227| on both ends are made by electric welding or otherwise closing the ends air tight; thus malin ing the string of electric lamps.

lt is obvious that the variable features previously referred to regarding and Fig. 6 will also apply to the lamps in Fig. 23 or Fig. 2i. Another feature of these lamps is that they are adapted to be substituted for either glass capillary tube assembly that is referred to in Patent 2,154,542, patented April 18, 1939, page 1, column 2, line 15, orpage 2, column 1, line 5, with one or several lamps being used as may be desired with individual lamps spot welded tothe lamps in Fig. 5.

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gether or with a string of lamps as shown in Fig. 22, Fig. 23 and Fig. 24. It is also obvious that any of the other electric pin-head lamps shown herein can be substituted for the glass capillary tube, and when they are filled with high pressure gas, an even greater gas pressure can be sustained therein because of the high pressure gas surrounding them within the outer thick wall bulb.

In the descriptions of the lamps shown in Fig. 6 to Fig. 24, several different ways are shown to construct the pin-head electric lamps and it is obvious that the sequence of operations described herein can be changed without lmaterially altering the finished lamp; also the parts of one lamp can be substituted for similar parts of other lamps, thus making other combinations of parts, for example the bulb in Fig. 10 can be substituted for the bulb in Fig. 1, Fig. 2, Fig. 3, etc., making many combinations; therefore a further object of this invention is that eachv part or each operation performed to assemble that part with another part shall be an improvement of this invention.

In Fig. 23 and Fig. 24 are shown strings of pinhead electric lamps which are ideally suited to make improved fluorescent lamps, by substituting them for the small lamps shown mounted in my previous invention Patent Number 2,137,732, patented Nov. 22, 1938, in which a reference is made to fluorescent bulb coatings on page 3, column 2, lines 7 to 23 inclusive. The lamps best suited for fluorescent lighting would be similar to those lamps shown in Fig. 1 and Fig. 4 of Patent 2,137,732. In the ordinary fluorescent lamp, which is practically a low pressure gas glow lamp having fluorescent material coated on the inside of the bulb, there arises the difficulty of making a compact lamp of sufficient wattage or total lumen output in a single unit that will give enough light for an ordinary size household room; for example some of those single unit tubular lamps, which barely give enough light for proper illumination, are approximately one and one-half inches outside diameter by fortyeight inches long (1l/2" O. D. x 48" Lg.) which makes them both expensive and clumsy for household lighting; also the ordinary size globular lamp seems to be impractical for constructing gas glow type fiuorescent lamps. In my invention a string of these pin-head electric lamps can be designed to have wattages that are comparable with most all sizes of household electric incandescent lamps and can be substituted and mounted in place of the wire filaments within those lamp bulbs; the inside surfaces of those tubular or globular glass bulbs are coated with a thin layer of fluorescent material such as zinc silicate which phenomenally changes the energy of invisible light rays to visible light rays and increases the lighting efficiency of the lamp. While the coating of fluorescent material has a certain amount of hiding and diffusing properties for' the other visible light rays, yet the gains made by fluorescence seems to offset it. In my previous invention Patent 2,137,732, the small lamps of my copending application Serial Number 190,615, now Patent Number 2,154,542, patented April 18, 1939, were mounted therein for fluorescent lighting effects and was duly referenced on page 3, column l, lines 2 to 5 inclusive. Now I claim that these pin-head electric lamps as individual lamps as in Fig. 5 and Fig. 6 that can be connected together, or the string of pinhead electric lamps interconnected as a single unit as in Fig. 23 and Fig; 24, are an ideal combination for making compact fluorescent, phos-` phorescent, or, luminescent electric lamps when mounted within a large bulb as previously described.

In Fig. 22, Fig. 23 and Fig. 24, the pin-head lamps are shown with their inside volumes all interconnected, and it is a further obectof this invention that this method of connecting small electric lamps together shall be one of the improvements of this invention, for example the small electric lamps shown in the previously mentioned patents (2,097,679; 2,137,732, 2,154.- 542) can also be interconnected by this method.

While it is obvious that the hollow metal wire is a convenient means of interconnecting the small electric lamps together, yet it is possible to interconnect them with glass tubing. One object in making a. series of small pin-head lamps that are interconnected withA glass tubing instead of being made in a longer tubular lamp like those in the patents mentioned in the preceding paragraph, is that the natural gem or quartz pebble bulbs can be untilized in electric lamp making that will withstand higher operating temperatures than the fused product of' the same material. Some gems are generally accepted as being infusible, such as diamond which will change to graphite at about 2200 degrees Kelvin temperature, however these infusible gems can be used close to the light source in a pin-head electric lamp and glass tubing with solid lead-in wires supported therein can interconnect between the pin-head lamp bulbs. When high pressure gas is sealed within such a string of pin-head electric lamps, the end bulbs can have hollow metal wires extending therefrom for exhausting, filling, and finally sealing the gas therein, while the other lamps in the string are interconnected with glass tubing. A string of such glass tube interconnecting gem bulb lamps could be manufactured by making pieces of glass tube which have their ends cupped out suficiently to enclose a gem that has previously been bored out for the lamp light source, inserting lead-in wires on supports within the glass tube, connecting a lamp filament or arcing electrodes to the lead-in wires, slipping the gem over the filament or arcing electrodes, butt sealing two cupped end tubes together by glass fusion to enclose the gem with the filament or arcing electrodes therein, and so on with the next lamps until the string of lamps are interconnected which can be exhausted and filled like the lamps in Fig. 22; therefore a further object of this invvention is to show that the method of interconnecting the inside volume of small electric lamps together, can be applied to small lamps having glass tubes connecting them as well as hollow metal wires connecting them; also a further object is to show that gem bulbs can be made with glass tubing connecting them as well as hollow metal wires connecting them. I

The size of the small spherical (tubular if desired) lamp bulbs most readily adapted to the improvements of this invention would have a range from one millimeter (1 mm.) to five millimeters (5 mm.) in diameter; however the smallest size to which it is possible to make them would depend upon the smallest size of the hollow metal wires. The smallest size or the exact limit as to how small it is possible to make a hollow metal wire or even a solid wire has never been determined; however solid platinum wire has been made as small as four microns (4 p) in dit llt

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accaoca' diameter. Such small platinum wire is made by making a small platinum core within a rod of steel, copper, or any other suitable wire drawing metal; then' the rod is reduced to fine wire by regular wire drawing processes, which at the same time reduces the platinum core to approximately the same proportional size in the iine wire m it was within the-original rod, then by dissolving the steel or other metal sheath of the iine wire with acid or other chemicals that will not attack the platinum, anV extremely fine platinum wire is made. This same method of malring an extremely fine solid platinum wire can be applied to making an extremely fine platinum hollow metal wire except that a platinum hollow core is reduced within the steel or other metal :line wire. The hole in the platinum core within the steel or other metal rod is mandreled as it is first reduced to a larger wire, then reduced without a mandrel by wire drawing to a line hollow metal wire that later has the outside sheath oi steel or other metal removed by acid or other chemicals. It is not possible to make such hollow metal wire as small in diameter as a solid wire, however the experiments with the larger hollow metal wire in wire drawing show or indicate that when the wall thickness of the hollow metal wire is equal to approximately one-half (Mq) oi its inside diameter the same metal can be made into a hollow metal wire which is approximately ten times (X) the diameter of a solid wire made of that same metal; for example l have had hollow metal wire made from stainless steel containing' from twenty-seven to thirty percent (27 to 30%) chromium that measured eighteen-thousandths inches (.018) outside diameter with five-thousandths inch (.0U5) wall, whereas this same metal can be reduced to solid wire from one-thousandth to two-thousandths inch (.001" to .002") outside diameter, in each case if the metal is drawn much smaller than these dimensions, breakage increases rapidly and it seems that the grain structure of the metal bears a direct relation to the minimum size to which it can be drawn. This analogy would a the present low limits of a platinum hollow metal wire at microns (fill n) in diameter, which could be sealed within a glass bead or bulb 100 microns (100 a) in diameter, and having tungsten arcing electrodes or a straight wire lament 1li microns (l0 a) in diameter which is approximately the diameter of the smallest tungsten wire or flament made, thus making the smallest electric lamp in the world.

The exclusive features of these pin-head electric lamps which permit them to be made smaller than any previously known electric lamps, can be readily understood by studying Fig. 13 to Fig. 2l inclusive, in contrast with other known methods of making extremely small electric lamps, such as the electric incandescent lamp known as the grain or wheat lamp; therefore this comparative explanation. Previously it was pointed out that the smallness of the pin-head electric lamp or bulb is controlled by the minimum size ci the hollow metal wires, whose outside diameter limits the inside diameter of the glass bulb as seen lh Fig. i3 and Fig. 14. Here a glass bead is made by cutting an extremely small diameter glass tube into short pieces. It is well known that glass tubes can be made one-tenth millimeter (11a nim.) outside diameter or even smaller, by drawing out a heated portion of a larger glass tube. Educh extremely small drawn-out tubing can be etched with a diamond point as it is ro tated in a chucklng device at intervals and broken oil. to make pieces no longer than the diameter of the tubing; thus making a glass bead which will ,lust freely slip over the smallest hollow metal wire. The entire glass bead is heated to its fusing temperature at the junction of the two hollow metal wires and when hermetlcally sealed thereto while still in a plastic state the hollow metal wires are separated enough to rorm the pin-head electric lamp bulb. Now a bulb made entirely of glass could be made just as small as this bulb with the hollow metal wires but it is the practical operations of mounting the electric lamp light source therein that maires possible the difference respectively in each lamp size. In the pin-head electric lamp no part ot the glass bulb is heated to its melting or plastic teinperature once the glass bulb is made because the light source is inserted through and connected to the hollow metal wires and also exhausted, gas lled, and finally sealed thereby; whereas in the grain of Wheat lamp, the ends of the glass bulb must be heated to its melting or plastic temperature to seal in the light source and its leadin Wires while the lamp is exhausted, gas lilled, and finally sealed air tight. In the grain of wheat lamp, the difllculty arises to seal in the lead-in Wires without heating the glass bulb to a point that it will collapse around the light source; to accomplish this the bulb must be made so much larger in proportion to the lead-in wire size that the glass will fuse to the lead-in wires before enough heat is conducted to the glass bulb to cause its collapse. In the grain of wheat lamp,

lthere must be two separate sections where the glass bulb is heated to its fusing temperature to seal in the two lead-in wires and iinally seal the lamp air tight and also a third section between them where the glass bulb is not heated enough to cause its collapse around the light source; to this extent are the features which limit the minn imum size that an electric lamp can be made by those previously known methods; whereas with the improvements of this pin-head electric lamp those type or limiting features do not exist; therefore the pin-head electric lamps can be made much smaller than any other electric lamps that are known at the present time. it is also obvious that these improvements for pin-head electric lamps can be used to maire lamps much larger than the grain of wheat lamp; however the methods used to construct the grain of wheat lamp could not be applied practically to conn struct a lamp as small as those possible with the piluhead lamp type ci construction similar to those progressive methods shown in Fig. 13 to Fig. 2l inclusive except that straight wire i'llaments or i'lne wire arcing electrodes are used in place of the coiled hlaments with lead-in wires therein.

ln all electric lamps the lead-in wires should extend a sul-licient distance beyond the lamp bulb to permit electrical connections to be made thereto and those lead-in wires are rightfully part of the lamp. ln a pin-head electric lamp due to the relative rigidity of the hollow metal wires enclosing the lead-in wires, their ends can be cut orf after sealing as close to the glass bulb as is practical, which permits a lamp to be mounted within a spring clip socket that resembles a pair of tweezers; thereby further reducing the actual size of the pin-head electric lamp.

A further object of this invention which has not been described in my previous inventions but lll dit

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still remalnsan improvement of the hollow metal wires, is that a wire filament light sourcecan be inserted through the hollow metal wires into the lamp bulb even though the glass bulb is hermetically sealed around the ho1lowmetal Wires.

The pin-head electric lamps described herein can be used for surgical electric lamps, flashlight electric lamps, dental electric lamps, or any other electric lamp that must be confined to small spaces; also they can be used within larger electric lamps that require very small intense light sources; or they can be connected in a string like beads and mounted openly or enclosed within larger lamp bulbs and surrounded by a vacuum, low pressure gas, high pressure gas, or any cooling liquid.

Whenever the word gem is herein referred to, it is intended to mean a natural stone that will either refract, reflect, or permit the transmission of light through it; or any stone manufactured by artificial or synthetic means to duplicate or imitate such natural stone; or any stone reconstructed by fusing natural or artiiicially made stones together; or stones known in the trade as precious or semi-precious stones. The chief stone which I have had in mind is the clear white transparent Zircon, however other stones such as quartz, sapphire, diamond, and many others can be used, which have good optical qualities, resistant to thermal shock, withstand intense heat and are of high mechanical strength to resist fracture.

Whenever the words hollow metal wire or quartz or glass or metallic vapor or metallic vapor lamen or high pressure gas or hermetically sealed or final seal are herein referred to, they are intended to have the same meaning as described in one or more of the previously mentioned patents (2,097,679; 2,137,732; 2,154,542) from which this invention is a continuation.

In view of the preceding description, it is obvious that the improvements of this invention can be used to make many more pin-head electric lamps and other electric lamps not referred to ,tric lamp invention is that it introduces a new type .of electric lamp construction or method whereby it is possible to build smaller electric lamps than can be made by any other known methods of construction. While it would be possible but not economically practical to build large spherical or tubular lamps as much as onehundred millimeters mm.) in diameter or even larger by using this pin-head type of construction, yet this type or method was developed especially for lamps that are smaller than any other known heretofore, and it is upon this type of construction wherein the real invention for the pin-head lamp originates; therefore it becomes the novelty lamp for such type of construction, whose ideal size would be approximately two millimeters (2 mm.) outside diameter and in some cases smaller, and others larger, but rarely over ten millimeters (10 mm.) outside diameter. Because the ideal size of the lamps is approximately two millimeters (2 mm.) in diameter, and would compare in size with the head of a common household or clothing pin. I have chosen the name of pin-head to identify these small electric lamps and the type of construction which was developed for their manufacture.

When a pin-head type of electric lamp bulb ls made larger than five millimeters (5 mm.) outside diameter, the effect of internal glass strains increases with disastrous results as the mass of glass becomes larger; also as the wall of the glass bulb become thicker, making a slower heat dissipating effect, the larger mass of glass hazard increases rapidly, especially so when the wattage of a lamp is made higher for the larger size bulb. Even with thermal shock resisting glass, like fused quartz, a high wattage light source will soon melt or soften the glass to destroy the bulb if the walls are too thick. For these principal reasons the smaller sizes of pin-head electric lamps are advocated.

When a pin-head type of electric lamp is made smaller than one millimeter (1 mm.) outside diameter, it approaches a class of one that has very little practical use at the present time other than being a mere .scientic toy or curiosity. I have thought and hoped that perhaps some day in the future, these extremely small pin-head electric lamps will become a part of scientific tools, unknown at present, whereby competent medical doctors and surgeons will use them to combat diseases, such as parasitic, bacterial, and Virus infection, or retard cancerous proliferation, or control gangrene by actinic light treatments.4 Due to the extremely small size to which the pin-head type of electric lamps can be made, the surgical instrument using them could be inserted directly to the point of infection with an incision that is not larger than one made by an average size hypodermic needle; also by the use of eosin and its derivatives the penetrating effect of the actinic light can be increased many fold together with the fact that the electric lamp would be at the local point of treatment and would produce what might be called nasent actinic light. In view of these possible developments the extremely small pin-head type of electric lamp may prove to be very useful to mankind and there is still much research ahead for it.

Some of the characteristics of the pin-head electric lamps, which distinguish them from any other type of electric lamp, are as follows: duev to its practical type of construction, the pin-head electric lamp can be made to smaller dimensions than any previously known electric lamp; the complete pin-head electric lamp bulb can be made without any light source parts therein; a pin-head electric lamp bulb can be made by butting the ends of two hollow metal wires together and by glass fusion, hermetically seal a glass bead at their junction, which are then separated a suitable distance while the glass is still in a plastic state to form the bulb; the light source parts can be inserted into the pin-head electric lamp bulb through the hollow metal wires; through the pin-head electric lamp development, a practical way has been found. to utilize gems in making electric lamps whose light source has a higher intensity in brightness than any previously known electric lamp, because natural gems can withstand higher temperatures than glass or fused quartz when enclosing high pressure metallic vapor; the pin-head electric lamp bulb can be made with a mechanically bored hole through it to enclose the light source, in either a glass bulb or a gem bulb; due to the small volume of material comprising a pin-head electric lamp bulb smaller than two millimeters (2 mm.) outside diameter, there will .be less internal strains within the bulb than is encountered in larger masses of glass; extremely small pin-head electric lamps will dissipate their own heatfaster than larger lamps, just like a small part or object will cool faster than a large one.

I claim:

l. An electric lamp bulb. consisting of. a gem having a mechanically bored hole through it to form a light source enclosure, two hollow metal wires extending from said hole in said gem, a glass bead hermetically sealed to said gem and said hollow metal wires enclosing said gem to form said lamp bulb.

2. A metallic vapor capillary bulb, consisting of, a gem having a mechanically bored bellmouth capillary hole through it to form a metallic vapor capillary hole, two hollow metal wires fitted into said bell-mouth capillary hole in said gem, a glass bead hermetically sealed to said gem and said hollow metal wires to form said capii lary bulb.

3. A pin-head electric lamp bulb, consisting of, a gem having a mechanically bored bell-mouthed hole through it to form a light source enclosure, two hollow metal wires hermetically sealed in said bell-mouth hole by glass fusion to form said lamp bulb.

4. An electric lamp bulb, consisting of, a geni having a mechanically bored hole through it to form a light source enclosure, two hollow metal wires butted against said gem in axial alignment with said hole in said gem, a glass bead hermetically sealed to said gem and said hollow metal wires by glass fusion to form said lamp bulb.

5. In combination with an electric lamp, the method of making an electric lamp bulb having a gem with a mechanically bored hole through it, said hole being the interspace of said bulb to envelope the light source of said lamp, coating said gem around the edges of said hole with a film of glass fusing flux, fusing glass to said gem around the edges of said hole by means of said flux, hermetically sealing two exhaust and gas filling tubes by glass fusion with the glass around the edges of said hole, said exhaust and gas 111iing tubes connecting with the interspace oi' said bulb.

6. In a pin-head electric lamp, the combination of, two hollow metal wires whose inner ends are in proximity with each other, an envelope of light transmitting material being hermetically sealed around the inner ends of said hollow metal wires to form a bulb, a light source within said bulb, said hollow metal wires being a means to communicate with said light source, lead-in wires being integral with said hollow metal wires for said light source, said hollow metal wires affording a means to naily seal said lamp air tight.

7. A pin-head electric lamp as set out in claim 6, wherein the envelope of light transmitting material is a glass bead.

8. A pin-head electric lamp as set out in claim 6, wherein the envelope of light transmitting material is a gem.

9. A pin-head electric lamp as set out in claim 6, wherein the space within the bulb is a near vacuum.

10. A pin-head electric lamp as set out in claim 6, wherein the space within the bulb is illled with low pressure gas.

11. A pin-head electric lamp as set out-in claim 6, wherein the space within the bulb is filled with high pressure gas.

12. Several pin-head electric lamps interconnested for exhausting and liing as a single unit, wherein each lamp is as set out in claim 6.

13. A pin-head electric lamp as set out in claim 6, wherein the space within the bulb has vaporizable metal therein.

14. A pin-head electric lamp as set out in claim 6, wherein the space within the bulb is lled with an ionizable gas.

15, A pin-head electric lamp as set out in claim 6, wherein the lead-#in wires are arcing electrodes.

16. A pin-head electric lamp as set out in claim '6, wherein an electric lamp iilament forms the light source.

17. An intense heat resisting electric lamp bulb, consisting of, a gem having a hole through it, said hole being a cavity to enclose an electric lamp light source, two hollow metal wires in the ends of said hole, said hollow metal wires her- 

